public class demo1 {
    public demo1(int b,int a) {
        this(0);
    }
    public demo1(int a) {
        ;
    }
    public static void main(String[] args) {
        StringBuffer a = new StringBuffer();
        String str = null;
        System.out.println(a.append(str));
        System.out.println(a);
    }


}
